Blood Alcohol Concentration and Pharmacodynamics

Question 1

How is Ethanol produced?

Answer 1

By fermentation of sugars by yeasts

Question 2

What is alcohol by volume (ABV)?

Answer 2

The number of mL of pure ethanol present in 100mL of solution

Question 3

What is Alcohol by weight (ABW)?

Answer 3

The number of grams of pure ethanol present in 100g of solution

Question 4

What are the physiological effects of Alcohol?

Answer 4

• Acts as a Central Nervous System (CNS) depressant
• At lower alcohol concentrations, higher brain functions are more affected.
• At higher alcohol concentrations, lower level brain functions are depressed

Question 5

What are the stages of intoxication?

Answer 5

1. Excitement - depression of inhibitory functions
2. Confusion - depression of brain functions such as memory, speech, etc.
3. Stupor - depression of brain functions such as breathing, circulatory functions, etc.

Question 6

What are the BACs for the stages of intoxication?

Answer 6

1. Excitement - less than 100mg %
2. Confusion - 100-200mg %
3. Stupor - greater than 200mg %

Question 7

What are the three main UK legislation that cover drink driving?

Answer 7

1. Road Traffic Act 1988
2. Transport and Works Act 1992
3. Railways and Transport Safety Act 2003

Question 8

What is the prescribed maxima for blood, urine and breath

Answer 8

Blood - 80mg/100 mL (80mg %)
Urine - 107mg/100 mL (107mg %)
Breath - 35μg/100 mL (35μg %)

Question 9

Absorption of Alcohol?

Answer 9

Diffusion through mucosal surfaces of GI tract
- 25% absorbed from stomach
- 75% absorbed from small intestine

Question 10

Distribution of Alcohol?

Answer 10

• Once absorbed, ethanol spreads to tissues as a function of their water content.
• Alcohol is distributed in tissues with high water content and more blood supply.
• The peak blood concentration is reached in 30 to 90 minutes.

Question 11

Metabolism of Alcohol?

Answer 11

• The majority of ethanol is metabolised to acetaldehyde, which is catalysed by ADH
• Most of acetaldehyde is oxidised to acetic acid, which is catalysed by ALDH.

Question 12

What is the Widmark equation used for?

Answer 12

It gives a rough estimate of peak blood alcohol concentration.

Question 13

What is the equation for BAC?

Answer 13

BAC = (Weight alcohol consumed (mg)) / (Body weight (kg) x WF x 10)

Question 14

What is the Widmark Factor for females and males?

Answer 14

Females - 0.55
Males - 0.68

Question 15

What is the equation for calculation of dose?

Answer 15

Dose = (Volume (mL)) x (Strength(%) / 100) x (density (g/ml)

Question 16

What is the density of alcohol?

Answer 16

= 0.789 g/mL

Question 17

How do you convert g to mg?

Answer 17

x1000

Question 18

How do you work out Elimination Rate of Alcohol?

Answer 18

Slow: 9mg
Average: 18mg
Fast: 27mg

Question 19

What is the therapeutic index?

Answer 19

The therapeutic index refers to the relationship between toxic and therapeutic doses
It also indicates the relative safety of a drug

A higher therapeutic index is preferable to a lower one.

Question 20

How can you calculate the therapeutic index?

Answer 20

Therapeutic Index = TD50 / ED50

Question 21

What is Pharmacology?

Answer 21

It’s a branch of medicine and pharmaceutical sciences which is concerned with the study of drug and medication action.

Question 22

What is Pharmacodynamics?

Answer 22

• Is how drugs work on the body
• The action of a drug on the body, including receptor interactions, dose response phenomena, and mechanisms of therapeutic and toxic action

Question 23

What are receptors and where are they located?

Answer 23

Receptors are protein molecules that receive chemical signals from outside a cell.
They are located on the cell surface membrane or within the cytoplasm

Question 24

What do activated receptors do?

Answer 24

They directly or indirectly regulate cellular biochemical processes.

Question 25

What are Ligands?

Answer 25

Molecules that bind to a receptor e.g. hormones, neurotransmitters, or drugs

Question 26

What is selectivity?

Answer 26

Selectivity refers to the degree which a drug acts on a given site relative to other sites.

Question 27

What is Affinity?

Answer 27

The probability of a drug occupying a receptor at any given time and this is determined by its chemical structure.

Question 28

What is Efficacy?

Answer 28

The measure of the bound ligand to activate its receptor. Intrinsic activity.

Question 29

What are agonist drugs?

Answer 29

- Drugs that interact with and activate receptors - They possess both affinity and efficacy - They desensitise receptors

Question 30

What are the two types of agonist drugs?

Answer 30

1. Full Agonists - maximal efficacy 2. Partial Agonists - less than maximal efficacy

Question 31

Give an example of full agonists?

Answer 31

- Morphine - Diamorphine - Methadone - Oxycodone

Question 32

Give an example of Partial Agonists?

Answer 32

- Buprenorphine - Nalmefene

Question 33

What are Antagonist Drugs?

Answer 33

Drugs that interact with a receptor but DO NOT change it. They have affinity but no efficacy. They upregulate receptors

Question 34

What are the two types of antagnoist drugs?

Answer 34

1. Competitive (competes with agonist for receptor) 2. Non-competitive (drug binds to receptor and stay bound)

Question 35

What is an example of an Antagonist?

Answer 35

Naloxone (Narcan)

Question 36

Dose-Response

Answer 36

The concentration of the drug at the site of action controls the effect.

Question 37

What are the three toxicity constants?

Answer 37

ED50 - Effective Dose TD50 - Toxic Dose LD50 - Lethal Dose

Question 38

What is the median effective dose? (ED50)

Answer 38

The drug dose producing 50% maximal effect, or the dose producing the desired effect in 50% of the population

Question 39

What is the median toxic dose (TD50)?

Answer 39

The dose producing a toxic effect in 50% of the population

Question 40

What is the median lethal dose (LD50)?

Answer 40

The dose producing a lethal effect in 50% of the population.

Question 41

What is NOAEL?

Answer 41

No observed adverse effect limit - The highest tested dose or concentration of a substance where no adverse effect is found.

Question 42

What is LOAEL?

Answer 42

Lowest observed adverse effect limit - The lowest dose or concentration of a substance that causes a harmful effect.